This is the first in a Daily Caller investigative series on Media Matters For America. Daily Caller reporters Alex Pappas and Will Rahn contributed to this report.

David Brock was smoking a cigarette on the roof of his Washington, D.C. office one day in the late fall of 2010 when his assistant and two bodyguards suddenly appeared and whisked him and his colleague Eric Burns down the stairs.

Brock, the head of the liberal nonprofit Media Matters for America, had told friends and co-workers that he feared he was in imminent danger from right-wing assassins and needed a security team to keep him safe.

The threat he faced while smoking on his roof? “Snipers,” a former co-worker recalled.

“He had more security than a Third World dictator,” one employee said, explaining that Brock’s bodyguards would rarely leave his side, even accompanying him to his home in an affluent Washington neighborhood each night where they “stood post” to protect him. “What movement leader has a detail?” asked someone who saw it.

Extensive interviews with a number of Brock’s current and former colleagues at Media Matters, as well as with leaders from across the spectrum of Democratic politics, reveal an organization roiled by its leader’s volatile and erratic behavior and struggles with mental illness, and an office where Brock’s executive assistant carried a handgun to public events in order to defend his boss from unseen threats.

Yet those same interviews, as well as a detailed organizational planning memo obtained by The Daily Caller, also suggest that Media Matters has to a great extent achieved its central goal of influencing the national media.

Founded by Brock in 2004 as a liberal counterweight to “conservative misinformation” in the press, Media Matters has in less than a decade become a powerful player in Democratic politics. The group operates in regular coordination with the highest levels of the Obama White House, as well as with members of Congress and progressive groups around the country. Brock, who collected over $250,000 in salary from Media Matters in 2010, has himself become a major fundraiser on the left. According to an internal memo obtained by TheDC, Media Matters intends to spend nearly $20 million in 2012 to influence news coverage.

Donors have every reason to expect success, as the group’s effect on many news organizations has already been profound. “We were pretty much writing their prime time,” a former Media Matters employee said of the cable channel MSNBC. “But then virtually all the mainstream media was using our stuff.”

The group scored its first significant public coup in 2007 with the firing of host Don Imus from MSNBC. Just before Easter that year, a Media Matters employee recorded Imus’s now-famous attack on the Rutgers women’s basketball team, and immediately recognized its inflammatory potential. The organization swung into action, notifying organizations like the NAACP, the National Association of Black Journalists, and Al Sharpton’s National Action Network, all of which joined the fight.

Over the course of a week, Media Matters mobilized more than 50 people to work full-time adding fuel to the Imus story. Researchers searched the massive Media Matters database for controversial statements Imus had made over the years. The group issued press release after press release. Brock personally called the heads of various liberal activist groups to coordinate a message. By the end of the week, Imus was fired.